Expand description
Pure Rust geographical projections library. Similar to Proj
in
basic functionality but allows for a use in concurrent contexts.
Projections’ implementations closely follow algorithms and instructions provided in: Map projections: A working manual (John P. Snyder, 1987)
This crate in very early stages of development. If you are interested in contributing do not hesitate to contact me on Github.
§Usage example
We can project the geographical coordinates to cartographic coordinates on a map with sepcified projection as follows:
// First, we define the projection
// We use LCC with reference longitude centered on France
// parallels set for Europe and WGS84 ellipsoid
let lcc = LambertConformalConic::new(2.0, 0.0, 30.0, 60.0, Ellipsoid::WGS84)?;
// Second, we define the coordinates of Mount Blanc
let (lon, lat) = (6.8651, 45.8326);
// Project the coordinates
let (x, y) = lcc.project(lon, lat)?;
// And print the result
println!("x: {}, y: {}", x, y); // x: 364836.4407792019, y: 5421073.726335758
We can also inversly project the cartographic coordinates to geographical coordinates:
// We again start with defining the projection
let lcc = LambertConformalConic::new(2.0, 0.0, 30.0, 60.0, Ellipsoid::WGS84)?;
// We take the previously projected coordinates
let (x, y) = (364836.4407792019, 5421073.726335758);
// Inversly project the coordinates
let (lon, lat) = lcc.inverse_project(x, y)?;
// And print the result
println!("lon: {}, lat: {}", lon, lat); // lon: 6.8651, lat: 45.83260000001716
Some projections are mathematically exactly inversible, and technically geographical coordinates projected and inverse projected should be identical. However, in practice limitations of floating-point arithmetics will introduce some errors along the way, as shown in the example above.
§Multithreading
For projecting multiple coordinates at once, the crate provides _parallel
functions that are available in a (default) multithreading
feature. These functions
use rayon
crate to parallelize the projection process. They are provided
mainly for convenience, as they are not much different than calling
.par_iter()
on a slice of coordinates and mapping the projection function over it.
let lcc = LambertConformalConic::new(2.0, 0.0, 30.0, 60.0, Ellipsoid::WGS84)?;
// Parallel functions use slices of tuples as input and output
let geographic_coordinates = vec![(6.8651, 45.8326); 10];
let map_coordinates = lcc.project_parallel(&geographic_coordinates)?;
let inversed_coordinates = lcc.inverse_project_parallel(&map_coordinates)?;
Modules§
- Geographical projections implemented by the crate.
Structs§
- Ellipsoid struct that defines all values contained by reference ellipsoids.
Enums§
- An interface for errors used within the crate and that the user may face.
Traits§
- An interface for all projections included in the crate.